NEW YORK (Reuters Health) - While heart transplant patients are living longer now than in years past, African Americans are still faring worse than patients of other races, a new study finds.
Researchers found that of just over 39,000 Americans who had a heart transplant between 1987 and 2009, the percentage of recipients who died within one to five years gradually dipped over time.
However, African Americans had higher death rates than white recipients, and the gap held steady over the two decades.
The new findings are published in the journal Circulation and are based on national data from the United Network of Organ Sharing, a non-profit organization that manages the U.S. organ transplant system.
Overall, 36 percent of black patients died within five years of their heart transplant. That compared to 26.5 percent of whites, 29 percent of Hispanic recipients, and 26 percent of recipients of other races and ethnicities.
When the researchers accounted for things such as age, type of heart disease and health insurance, only African Americans were at a higher risk of dying than whites.
While the reasons are not entirely clear, the findings do point to one factor, according to lead researcher Dr. Vincent Liu.
Immune system suppression — with drugs designed to keep the body from rejecting the donor heart — may not be working as well for black patients, Liu told Reuters Health in an email.
He and his colleagues found that black heart recipients were more likely than others to die because the donor heart failed or due to other heart problems. And some of those complications could have been due to inadequate immune system suppression, the researchers say.
Black patients were also more likely to be hospitalized within two years of their transplant, including for episodes of organ rejection.
On the other hand, patients of other races were more likely than African Americans to die of infections or cancer — which could be due to over-suppression of the immune system.
“The cause of the disparity (in death rates) appeared to result, at least in part, from differences in immunosuppression,” said Liu, of Stanford University in California.
The study cannot, however, show why those differences exist.
The lifelong care for transplant recipients involves striking a balance between too much and too little immune suppression, Liu explained. And erring significantly in either direction is dangerous.
The problem, Liu said, is that doctors have no simple test for measuring whether a patient’s immune suppression is “adequate.” Instead, they have to rely on other markers, like a patient’s blood levels of the immune-suppressing drugs, to adjust the medication doses over time.
And that may be missing important racial differences in drug absorption or side effects, Liu explained.
He added that past studies suggest that income and other social factors could be playing a role in black heart recipients’ poorer prognosis. They may have a harder time accessing all the care they need, or sticking with their lifelong treatment regimen.
After a heart transplant, people must adhere to a strict schedule of multiple medications, make regular trips to the doctor and change any unhealthy lifestyle habits. All of that could be more difficult for less-advantaged patients.
But there is also hope that the race gap can be closed.
Liu said that in an earlier study of lung transplant recipients, he found that the survival difference between white and black patients declined and disappeared after 2001.
So while Liu said he was “somewhat surprised” to see the persistent gap among heart transplant patients, the experience with lung transplants shows that it is possible to eliminate racial disparities in survival.
Liu said more detailed studies are now needed to uncover the precise reasons for the racial differences in immune suppression and heart transplant survival.
SOURCE: bit.ly/k6tG2K Circulation, online April 4, 2011.